for just throttle response, I really liked the pbx. I have the AA tune now, but before that the pbx gave the car much better throttle response (I have an automatic though). You can also just run it without the tune if you don't think the tune is smooth enough.

They are a pretty good deal if you can pick one up used.

I never did get why better throttle response is as crucial for automatics though. But for manuals you do need predictable response and feel, and for me, I found that the PBX just took away the predictable throttle in most cases and made it quite jerky overall. If it was able to rid the throttle of the delay then this would have been a different story, but since it is simply modifying the default throttle map, it cannot affect this. I reckon, get rid of the throttle delay, and that by itself will yield a far far better throttle for all driving conditions - accurate lightning fast or slower gear changes would be so much easier and consistent.